Track star 80amp esc with 13.5 motor combo

[corsa148]

Had a few of these track stars but the 120amp versions and had know bother but fitted this one for a friend and when trying to set it up once I have set the nutral zone then try to set full throttle it will not set the only way it will if I do reverse then throttle but as you can imagine you have full throttle in reverse any help would be great